Syeda Refat Sultana

Application of CSM-CERES-Maize model in optimizing irrigated conditions:

Maize is one of the main cereal crops in Pakistan with sensitivity to drought at various developmental stages known to influence the yield. The impact of variable weather conditions on maize yield can be analyzed with crop simulation models. The CSM-CERES-Maize model has been widely used to assess irrigation strategies for maize. This research was conducted to test the CSM-CERES-Maize model for its ability to accurately predict maize biomass and grain yield under water limiting and non-limiting conditions in semiarid conditions. Four growth stage-based irrigation treatments and two potential soil moisture deficit-based treatments were defined. During model calibration, the simulated maximum leaf area index (LAI), total dry matter (TDM), and grain yield were all within 10% of observed values. During model evaluation, there was generally satisfactory agreement between observed and simulated values for two hybrids (Monsanto-919 and Pioneer-30Y87) with the model showing variability of −17.9–20.0%, −9.2–14.3%, and −19.6–19.9% for maximum LAI, TDM, and grain yield, respectively, for the two hybrids among various treatments. The CERES-Maize model was useful in providing information to decision-making regarding diverse irrigation regimes at the farm level in a semiarid environment.

Normalized Difference Vegetation Index as a Tool for Wheat Yield Estimation: A Case Study from Faisalabad, Pakistan

For estimation of grain yield in wheat, Normalized Difference Vegetation Index (NDVI) is considered as a potential screening tool. Field experiments were conducted to scrutinize the response of NDVI to yield behavior of different wheat cultivars and nitrogen fertilization at agronomic research area, University of Agriculture Faisalabad (UAF) during the two years 2008-09 and 2009-10. For recording the value of NDVI, Green seeker (Handheld-505) was used. Split plot design was used as experimental model in, keeping four nitrogen rates (N1 = 0 kg ha−1, N2 = 55 kg ha−1, N3 = 110 kg ha−1, and N4 = 220 kg ha−1) in main plots and ten wheat cultivars (Bakkhar-2001, Chakwal-50, Chakwal-97, Faisalabad-2008, GA-2002, Inqlab-91, Lasani-2008, Miraj-2008, Sahar-2006, and Shafaq-2006) in subplots with four replications. Impact of nitrogen and difference between cultivars were forecasted through NDVI. The results suggested that nitrogen treatment N4 (220 kg ha−1) and cultivar Faisalabad-2008 gave maximum NDVI value (0.85) at grain filling stage among all treatments. The correlation among NDVI at booting, grain filling, and maturity stages with grain yield was positive (R 2 = 0.90; R 2 = 0.90; R 2 = 0.95), respectively. So, booting, grain filling, and maturity can be good depictive stages during mid and later growth stages of wheat crop under agroclimatic conditions of Faisalabad and under similar other wheat growing environments in the country.

Fate of Organic and Inorganic Pollutants in Paddy Soils

Paddy soils have a heterogenous nature, with complex physico-chemical interactions and varying soil characteristics. Paddy soils remain flooded and are considered as rich sources of nutrients for plant growth. The nutrient levels mostly depend on different management practices, such as fertilizer application, irrigation, and tillage, and the movement of nutrients in the soils. These paddy soils normally show less movement of applied nutrients out of the medium than other soils, because of stagnant water that reduces the mobility rate. Paddy soils can become polluted by anthropogenic practices such as the use of sewage wastewater; industrial wastewater containing heavy metals; fertilizers; and pesticides, and the leakage of petrochemicals. Some natural pollutants can be oxidized by microbial activity, but most pollutants do not undergo biotic and chemical degradation. Inorganic (heavy metals) and organic pollutants (polychlorinated biphenyls, polychlorinated dibenzodioxins, and polychlorinated dibenzofurans) are the major types of pollutants in paddy soils. The numerous organic and inorganic pollutants resulting from anthropogenic activities can remain for long periods in nature and can be transported over long distances. In particular, organic pollutants can be bioaccumulated and biomagnified, thus reaching high levels that can be dangerous for human wellbeing and biological communities. Inorganic pollutants such as the heavy metals Pb, Cr, As, Zn, Cd, Cu, Hg, and Ni cause hazards for human health, for plants, for animals, and for the fertility status of the soil. These heavy metals are common pollutants in paddy soil and they bioaccumulate; in this way the concentrations of these pollutants increase in living systems, owing to their retention rates being higher than their discharge rates in these systems. The fate of these pollutants depends on their bioavailability, degradation by microorganisms, adsorption, desorption, leaching, and runoff. The transport and degradation of these pollutants in paddy soils and groundwater results in contamination. The physico-chemical characteristics of the paddy soil framework; for example, the water content, soil organic matter, presence of clay, and pH, influence the sorption or desorption and degradation of pollutants and also influence leaching to the groundwater and runoff to surface waters. The translocation of natural pesticides in paddy soils depends upon the ionic or neutral behavior of the soil constituents, on the pesticides’ solubility in water, extremity on the substance, and the colloidal nature of the paddy soils.

Paddy Land Pollutants and Their Role in Climate Change

Climate change is one of the biggest concerns because its potential impact on human life is severe. The contribution ratio of CH4, CO2, and N2O to global warming would be high even if their emission rates are small. Paddy lands may become polluted by the aggregation of several pollutants, i.e., organic and inorganic fertilizers; discharges from the quickly extending industrial territories; use of manure, and organic solid waste; and wastewater irrigation system. Paddy lands are considered to be a major source of anthropogenic greenhouse gas (GHG) emissions through methanogenesis (a process of methane production), a microbial process that is strictly restricted to paddy fields. Overall 90% of rice land is at least temporarily flooded and produces GHGs at higher rates. The production of N2O in soils occurs during nitrification, denitrification, and microbiological processes. A positive relationship was found between the climate change and N fertilizer application with N2O emissions from paddy lands. The use of N fertilizer also stimulates and influences the CH4 emission flux between paddy land and atmosphere. The impact of biochar amendments on the CH4 emission expanded by 35.16–40.62% in paddy fields. It is of incredible concern worldwide that gaseous outflows from management of organic solid waste add to local and worldwide scale ecological procedures, for example, eutrophication, fermentation, and climate change. CH4 is generated from the disintegration of organic matter (OM) in anaerobic conditions by methanogens. Soil OM is the most well-known constraining element for methanogenesis in paddy fields. OM obtained from three primary sources: animal fertilizer, green manure, and crop deposits. The amendment of OM, for example, rice deposits and compost application, prompts expanding CH4 outflows because of anaerobic decay and results in climate change.